import { onRequest } from "firebase-functions/https";
import type { Request } from "firebase-functions/https";
import { requireAuth } from "../middleware/auth";
import { HttpError, sendError } from "../middleware/errors";
import {
  getMessages,
  getQuota,
  getSuggestions,
  reportMessage,
  sendMessage,
} from "../services/chatService";
import type {
  ChatHistoryPageDto,
  ChatQuotaDto,
  ChatReportDto,
  ChatSendResultDto,
  ChatSuggestionsDto,
} from "../types/dto/chatDto";

/**
 * AI 채팅(짹) 엔드포인트(§3). `/chat/*` 전체가 인증 필요 API다.
 *
 * - POST /chat/messages                      메시지 전송(비스트리밍, §3.1)
 * - GET  /chat/messages                      대화 이력 조회(§3.2)
 * - GET  /chat/quota                         오늘 잔여 횟수(§3.3)
 * - POST /chat/messages/{messageId}/report   메시지 신고(§3.4)
 * - GET  /chat/suggestions                   추천 질문(§3.5)
 *
 * 기본 AI 벤더는 Vertex AI(Gemini, ADC 인증 — 별도 키 불필요)다(§8).
 * 벤더 전환은 config/chat.provider.name으로: "mock" | "vertex" | "anthropic".
 * anthropic 전환 시 `firebase functions:secrets:set ANTHROPIC_API_KEY` 등록과 함께
 * 아래 onRequest 옵션에 `secrets: ["ANTHROPIC_API_KEY"]`를 추가한다(§8.2).
 */
/** 401 응답에 에러 코드 UNAUTHENTICATED를 포함한다(§3.1 에러 표 계약). */
async function requireChatAuth(req: Request): Promise<string> {
  try {
    return await requireAuth(req);
  } catch (err) {
    if (err instanceof HttpError && err.status === 401 && !err.code) {
      throw new HttpError(401, err.message, "UNAUTHENTICATED");
    }
    throw err;
  }
}

export const chat = onRequest({ timeoutSeconds: 60 }, async (req, res) => {
  const segs = req.path.replace(/^\/+|\/+$/g, "").split("/").filter(Boolean);

  try {
    if (segs[0] === "messages" && segs.length === 1) {
      const uid = await requireChatAuth(req);
      if (req.method === "POST") {
        const result: ChatSendResultDto = await sendMessage(uid, req.body ?? {});
        res.status(200).json(result);
        return;
      }
      if (req.method === "GET") {
        const cursor = req.query.cursor != null ? String(req.query.cursor) : undefined;
        const limit = req.query.limit != null ? String(req.query.limit) : undefined;
        const result: ChatHistoryPageDto = await getMessages(uid, cursor, limit);
        res.status(200).json(result);
        return;
      }
    }

    if (segs[0] === "messages" && segs.length === 3 && segs[2] === "report" && req.method === "POST") {
      const uid = await requireChatAuth(req);
      const result: ChatReportDto = await reportMessage(uid, segs[1], req.body ?? {});
      res.status(200).json(result);
      return;
    }

    if (segs[0] === "quota" && req.method === "GET") {
      const uid = await requireChatAuth(req);
      const result: ChatQuotaDto = await getQuota(uid);
      res.status(200).json(result);
      return;
    }

    if (segs[0] === "suggestions" && req.method === "GET") {
      const uid = await requireChatAuth(req);
      const result: ChatSuggestionsDto = await getSuggestions(uid);
      res.status(200).json(result);
      return;
    }

    res.status(404).json({ error: `Unknown: ${req.method} ${req.path}` });
  } catch (err) {
    sendError(res, err);
  }
});